Neurosurgical patients who need a brain tumor, epileptic region or other structural lesion removed that might be near language cortex require an invasive 45 min procedure (intra-operative electrical stimulation mapping; ESM) to map language and motor function and guide the neurosurgeon's operative approach. The information gained from ESM is critical to spare language areas and has been shown to improve post-operative morbidity. The methods used in this mapping procedure have remained unchanged for 60 years. The procedure requires passing current into the patient's brain to temporarily disrupt function and is associated with problems such as seizure induction during surgery. Further, the procedure typically takes 45 minutes, is not well tolerated in many patients and must be aborted in up to 25% of cases. Hence, a new method to map language is needed. The goal of this proposal is to assess whether high gamma activity (70-250 Hz) in the human electrocorticogram (ECoG) can be used to accurately and rapidly track critical language cortex in the operating room. It is hypothesized that high gamma activity, a likely index of cortical activation, can aid surgeons identify critical language areas and potentially replace classic intra-operative ESM eliminating the risks associated with this procedure and shortening the surgical time. In order to investigate this issue, two studies will be conducted. First, we will record ECoG in the awake neurosurgical patient in the operating room during the picture naming/number counting study traditionally employed by neurosurgeons. Second, we will perform a brief verb generation study in the OR in these same patients. It is predicted that during picture naming and number counting regions showing arrest during ESM will elicit high gamma activity. We further predict that the high gamma map of language obtained in the verb generation task will also correlate with the stimulation mapping results obtained during study one. If obtained the results would provide evidence that language mapping using ECoG and high gamma recording might provide a safer and faster alternative method to the traditional intra-operative ESM method resulting in reduced intra-operative morbidity and improved post-surgical outcome. Neurosurgeons need to identify critical language areas in the human brain to avoid causing a language problem when removing tumors and other brain abnormalities. The current method to accomplish this requires a 60 year old approach that has serious side-effects such as causing a seizure in the operating room. We propose to apply a novel method of brain electrical analysis to replace the traditional method employed. If successful the results would lead to safer and more effective neurosurgical procedures. [unreadable] [unreadable] [unreadable]